The meters are usually installed to prevent customers having their energy cut off.
Many pre-payment customers are among the five million people who are listed as being in debt to their energy supplier.

And around 500,000 were “forced” to have pre-payment meters installed over the past six years, figures show.

A study by Citizens Advice also found they pay an average of 22 per cent more for energy than ordinary customers.

SWITCH AND CUT COSTS BY £238

THE Sun is giving readers a chance to cut their energy bills by a fifth and save £238 a year.

Our dual-fuel tariff, launched with The Big Deal and supplied by iSupply Energy, is one of the cheapest available.

The deal, fixed for 33 months, will cost just £825 per year on average.

A 12-month £999 deal is available for pre-payment customers — meaning everyone can save.

- The Big Deal receives a commission of £40 for each Sun reader who switches both electricity and gas. The Sun makes no money from the deal.

The Competition and Markets Authority, which investigated the energy industry, said: “Consumers on pre-payment meters get the raw end of the deal.

“They have much less choice than other customers because of the meters they use.”
The regulator has called for a cap on pre-payment costs but it will not come into force until April next year.

No exact amount has been set but it is thought to cut just £75 off a typical pre-payment meter bill.